There are many situations in which a cable passes from one environment where an extensive electromagnetic interference field exists through a shielding wall into a second environment to interconnect with equipment that could be easily damaged or made inoperative by induced interference signals. Accordingly, it is highly desirable in such situations to effect grounding or termination of the cable shield at the enclosing shielding wall which would be effective to ground any interference signals induced into the cable shield by interfering electromagnetic fields in the first environment and thereby prevent access of such potentially damaging signals to the equipment in the shielded environment.
For example, on board ship an intense interference field is produced by the ship's radar which can produce an interference signal of sufficient magnitude to completely disrupt and even, perhaps, destroy equipment handling low level signals.
A common approach to grounding a cable shield in the past has been to use a one-point connector ("pig tail") which although removing a certain amount of induced signals may not be sufficiently effective to remove enough of the interference signals to fully protect equipment connected to the cable wires.
Another approach to solving this problem is disclosed in copending U.S. patent application Ser. No. 642,170 filed Aug. 20, 1984, CABLE SHIELD GROUNDING APPARATUS by M. K. Van Brunt and G. E. Walters, which application is assigned to the same assignee as the present application. As shown there, a band of outer insulation is removed from the cable leaving a bare ring of cable shield exposed. A bandlike leaf spring having a plurality of radially inwardly directed edges is received about the bare shield with the edges contacting the shield. A hollow cylindrical member is received on the cable with its internal walls pressing the leaf spring tightly against the shield. A cap is threaded onto the cylindrical member, and the cylindrical member is received within an opening in a ground plane and welded to the ground plane immediately adjacent the opening.
A U.S. patent application assigned to this same assignee, Ser. No. 540,127 filed Oct. 7, 1983 now U.S. Pat. No. 4,547,623, CABLE SHIELD GROUNDING APPARATUS by M. K. Van Brunt and P. Madle locates one or more first conductive rings in contact with a base shield portion on the cable. A metal split-cylinder is disposed over the first conductive rings pressing them against the shield. A second metal ring and a rubber O-ring securely holds it in place. A cylindrical part received on the cable has an internal bore of such dimensions as to make flush contact with the second metal ring. A cap assembly encloses the cylindrical part, the latter being welded to the sides of an opening in a grounding plane.